Ring network system

Abstract

A ring network system (1) has at least one node M which acts as a master or sender node to transmit an outgoing signal (O.S.1) having a relative address determined according to the relative location of the addressee node in the system. As the outgoing signal passes through each node in turn, it is changed and a node recognizes that it is the addressee node if the relative address has a predetermined common addressee value. The addressee node generates a return signal (R.S.1) with a node identifier which is transmitted in the opposite direction to the outgoing signal and the sender node ensures that this is received for a valid poll. The master node (M) may automatically configure itself by retrieving the identifier of all nodes in response to outgoing signals. This allows nodes to be easily added or deleted. Each node on the return path adds data which it has captured together with its identifier so that data may be captured from all nodes between the sender node and the addressee nodes. A node (M) may transmit outgoing signals alternately in opposite directions in a manner whereby the addressee nodes are selected so that each communication link (3-8) is omitted in sequence and fault diagnosis takes place.

We claim: 
     
       1. A ring network system comprising: a plurality of nodes, each node comprising means for capturing data;   communication links interconnecting the nodes in a ring configuration;   control means in at least one sender node comprising means for: transmitting an outgoing signal to an addressee node, said signal having a relative address determined according to the relative location of the addressee node in the ring network, and   receiving a return signal from the addressee node and reading an addressee node identifier and captured data incorporated in the return signal;     data transfer means in each node comprising means for: receiving an outgoing signal, monitoring the relative address, and determining if it is the addressee node,   re-transmitting the outgoing signal to a next node if it is not the addressee node,   in response to reception of the outgoing signal, generating a return signal including captured data and transmitting said return signal to the sender node on a return path in the opposite direction to that of the received outgoing signal through nodes of the system if it is the addressee node, said return signal incorporating the identifier of the addressee node, receiving a return signal and determining that it is a return signal, and   adding captured data and the node identifier to said signal and re-transmitting the signal to a next node on the return path.     
     
     
       2. A ring network system as claimed in claim 1, wherein the data transfer means of each node comprises: means for changing the relative address of an outgoing signal before re-transmitting it to the next node whereby the relative address is dynamically maintained; and   means for determining if the node is the addressee node if the relative address has a pre-set common addressee value.   
     
     
       3. A ring network system as claimed in claim 1, wherein the relative address is a count value, and the data transfer means of each node comprises means for: receiving a signal and determining according to the count value if said signal is an outgoing signal, and determining if the node is the addressee node if the count value has a pre-set common addressee value; and   if the signal is an outgoing signal and the node is not the addressee node, changing the count value in a pre-determined manner and re-transmitting the signal to the next node.   
     
     
       4. A ring network system as claimed in claim 3, wherein the data transfer means comprises means for changing the count value by decrementing it. 
     
     
       5. A ring network system as claimed in claim 1, wherein the data transfer means comprises means for determining that a received signal is a return signal if the relative address has a pre-set common return signal value. 
     
     
       6. A ring network system as claimed in claim 1 wherein the control means comprises: means for transmitting a polling signal to every node location of the system using said relative addresses;   means for monitoring return signals from the nodes and reading the identifiers in said return signals; and   means for updating a table in a non-volatile memory correlating node locations with identifiers, whereby automatic configuration of the system takes place.   
     
     
       7. A ring network system as claimed in claim 6, wherein the control means comprises means for automatically performing said automatic configuration operations upon detection of a fault. 
     
     
       8. A ring network system as claimed in claim 1, wherein the control means comprises means for transmitting different outgoing signals in opposite directions to omit a communication link to assist in fault detection. 
     
     
       9. A ring network system as claimed in claim 8, wherein the control means comprises means for: sequentially omitting communication links in order around the system in successive outgoing signal cycles; and   monitoring the return signals and carrying out fault diagnosis processing based on data in said return signals.   
     
     
       10. A ring network system as claimed in claim 1 wherein said data transfer means comprises a signal repeater buffer amplifier. 
     
     
       11. A ring network system as claimed in claim 1, further comprising a remote infra-red user interface, and an infra-red module in the data transfer means of each node programmed to transmit node status information to the user interface when requested.